Airplane



Feb. 25, 1930;

L. C. MILBURN AIRPLANE Fil ed June 1927 UNVENTOR LesaiferCiMiLbarn mvw AT TO RNEYS i Patented Feb. 25, 1930 UNITED STATES-PATENT O F LESSITER C. MILBURN, OF CLEVELAND, OHIO, ASSIGNOR TO THE GLENN L. MARTIN COMPANY, OF- CLEVELAND, OHIO, A CORPORATION OF OHIO Application filed me 9, 1927. Serial m. 197,533.

This invention relates to improvements in airplanes, particularly twin-engined airplanes of the outboard type. Where the conventional arrangement of motors and propellers is followed in this type of airplane, that is, with the axes of the motors. and propellers arranged parallel tothe main axis or center line of the machine, considerable difliculty is experienced in directing or steering the airplane when one of the engine's stops. *When this occurs, the thrust of the other propeller tends to advance that side of the machine and therefore to turn the machine horizontally. To counteract this effeet, the pilotis forced to throw the rudder hard over and he then has no rudder movement remaining to enable him ,to turn the machine toward the side upon which the live engine is mounted.

One'of the objects of my invention, therefore, is to overcome the difficulty above ex-- plained, or, in other words,.to maintain the airplane in its course automatically when one engine stops.

Another object is to facilitate the guiding of a twin-engined airplane when the pilot is taxying. M

Other objects and features of novelty will appear as I proceed with the description of that embodiment of the invention which, for the purposes of the present application, I have illustrated in the accompanying .drawing, in which: p

Fig. 1 is a more or less diagrammatic plan view of a twin-engined airplane embodying my invention.

In the drawing, the fuselage is indicated at 1, and its principal axis, as well as the longitudinal center lineof the machine, at A-A. The wing cell is shown at 2, with engine na celles 3 and 4 mounted therein. The rincipal axes of the nacelles are marked Band as shown herein are parallel with the line AA. The two engine propellers shown at 5. and 6 are mounted for rotation at the forward ends of the nacelles 3 and 4,

being driven by engines located therein. The axes of rotation of these propellers are inclined outwardl toward the front toa slight extent. 'l hese axes are'indicated in the drawing at 0-0. The angle between the lines 'BB and C0 will vary more or less according tothe design of the airplane, the distance of the propeller hubs from the line AA, the length of the fuselage, and so forth, but to the best of my knowledge at the present time, this angle in practical embodiments ofthe invention should be somewhere between 29 and 10. At the tail end of the fuselage and located in a vertical planewhich includes the line l}-A is'a fin 7, the ordinary function 'of which -is a stabilizing one, but which has a new and additional function in .the present case as will later appear. At the rear of the fin 7 there is hinged the usual rudder 8. 'A stabilizer 9 of conventional ,form is also located at the tail end of the machine and has elevators 10 and 11 at its rear edge, theelevators being interrupted atthe middle of the machine only enough to give free swing to the rudder 8.

' Now in the flying of an airplane equipped with my invention when one motor stops running and the propeller driven thereby ceases to turn, the direction of movement of the airplane is not changed appreciably. Assume that the propeller 6 stops while the propeller.5 continues to turn. With the propellers mounted in the conventional manner, the airplane would then veer to the left. But with the angular arrangement of the propeller axes disclosed herein the cylinder of air which constitutes the slip stream from propeller 5, having its axis in the line CC, impinges upon the right side of film 7 and tends to swing the tail end ofthe machine to the left. By properly designing the parts, this effect can be made to equal the beforementioned tendency to turn the forward end to the left, and consequently with these two over what is necessary when the fin 7 is located in the path of the slip stream.

The speed of an airplane on the ground, particularly when it is just getting under way, being low, the effect of the rudder and of the elevators is not strong at such times, that is "to say, where twin propellers are mounted in the heretofore conventional manner. Where my mounting is employed, however, the slip streams from both propellers impinge vupon-the rudder and upon the elevators through practically the entire extent of the latter. Consequently, the tail of the machine responds to the movement of the rudder easily and quickly even at extremely low speeds of taxying.

Having'thu s described my invention, I claim:

1. In an airplane, two engine nacelles mounted upon opposite sides of the longitudinal center line of the machine, said na-- celles having their principal axes parallel to the said longitudinal center line of the machine, and propellers mounted to rotate upon fixed hearings in said nacelles with their axes of rotation inclined outwardly toward the front. 7 4

2. In an airplane, two en 'ine nacelles mounted upon opposite sides 0? the longitudinal center line of the machine, said nacelles having their principal axes parallel to the said longitudinal center line of the machine,

propellers mounted in said nacelles to rotate upon fixed bearings, and means for causing the slip streams from'said propellers to incline inwardly toward the rear.

In testimony whereof, I hereunto aflix my signature.

- LESSITER C. MILBURN. 

